Linear ablation assembly

ABSTRACT

An intravascular device for the formation of linear lesions which has particular utility in the treatment of atrial fibrillation and flutter. The intravascular device has an outer delivery member with a distal section which has an elongated opening and a support element coextending with the opening. An EP device having a plurality of electrodes on its distal section is slidably disposed within the inner lumen of the delivery member but it is secured by its distal end within the distal extremity of the delivery member at least while in operation. In this manner an axial force in the proximal direction on the proximal extremity of the EP device, which extends out of the patient during the procedure, will cause the distal shaft section of the EP device to arch outwardly out of and away from the distal section of the delivery shaft along an inner side of the curved distal section and engage the surface of the patient&#39;s heart chamber. RF electrical energy delivered to the electrodes on the distal shaft section of the EP device will form a linear lesion which terminates the fibrillation or flutter.

This invention is a continuation-in-part of U.S. patent application Ser.No. 08/629,057, entitled LINEAR ABLATION ASSEMBLY, filed Apr. 8, 1996,the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

This invention generally relates to the detection and elimination ofcardiac arrhythmia and particularly atrial fibrillation.

Atrial fibrillation is the disorganized depolarization of a patient'satrium with little or no effective atrial contraction. This conditionmay be chronic or intermittent, and it presently affects approximately 2million or more people in the United States alone. For atrialfibrillation refractory to conventional drug therapy, it has beenconventional practice to make incisions in the atrial wall, tosurgically segregate the tissue thereof, to discontinue the atrialfibrillation. The atrial segments formed by the surgical segregation areelectrically isolated and too small to allow the fibrillation tocontinue. However, the surgical technique is quite traumatic and isunacceptable to a large fraction of those patient's experiencing atrialfibrillation or flutter. Avitall in U.S. Pat. No. 5,487,385 disclosesthe use of high frequency electrical energy with a specificintravascular electrophysiological (EP) device to form linear ablationswithin a patient's atrial chamber to provide results similar to thesurgical techniques in terminating atrial fibrillation but withsignificantly reduced trauma. However, the Avitall device cannot bereadily placed within the patient's atrial chamber and provide thenecessary contact between the electrodes on the device and the atrialtissue to generate linear lesions of a requisite length when RFelectrical energy is emitted from the electrodes.

What has been needed is an ablation assembly which can be readilymanipulated within a patient's atrial chamber to generate effectivelinear lesions at any desired location within the atrial chamber. Thepresent invention satisfies these and other needs.

SUMMARY OF THE INVENTION

This invention is directed to an intravascular assembly suitable forforming linear ablations within a chamber of a patient's heart, which isparticularly suitable for treating atrial fibrillation and flutter.

In a broad sense the assembly of the invention comprises a deliverymember with an inner lumen extending therein, and an elongated supportelement in a distal section of the delivery member, and an elongated EPdevice disposed within the inner lumen of the delivery member and fixedby its distal end within the distal portion of the delivery member. Theelongated support element is coextensive at least in part with anelongated opening in a distal section of the delivery member.

Longitudinal movement of the EP device within the inner lumen of thedelivery member causes the distal portion of the EP device to arcuatelyextend out and away from the distal section of the delivery member. Thesupporting member in the distal portion of the delivery member providessupport to the distal end of the EP device and ensures that the distalportion of the EP device completely engages the inner surface of thepatient's heart chamber along a length thereof for emitting highfrequency (RF) electrical energy for the purpose of effective linearablation of heart tissue within the patient's heart chamber.Additionally, the electrode may be used for the collection of electricalsignals from the surface of the atrial chamber.

Effective detection of electrical activity is necessary to accuratelylocate the arrythmogenic site where the linear ablation is to occur andfor effective tissue ablation in a linear fashion to isolate sections ofthe atrial wall defining the heart chamber. The EP device of theassembly has a plurality of electrodes on the distal portion thereofwhich may be used for both sensing or ablating. The outer dimensions ofthe distal portion of the EP device are generally less than 5 Fr.,preferably less than 4 Fr., in diameter.

In one presently preferred embodiment, the supporting member of thedelivery member is a metallic ribbon which has an elongated flat surfacewhich faces the elongated opening in the distal section of the deliverymember. It may be made from high strength materials such as stainlesssteel, pseudoelastic NiTi alloys in an austenite phase. The supportelement is preferably manually shaped into a curved or angled conditionto facilitate entry of the distal extremity of the assembly within thepatient's heart chamber, particularly the right atrium, and the properpositioning of the extended distal section of the EP device against theinner surface of the heart chamber. Additionally, an elongateddeflection line may be provided in a wall of the delivery member, fordeflecting the distal section of the delivery member into a curved orangled condition.

The inner radius of the extended distal section of the EP device iscontrolled by the length of the elongated opening in the delivery memberand the distance the EP device is spaced from the support element. Theeffective length of the elongated opening can be controlled by thelongitudinal location of the distal end of a sheath disposed about theexterior of the delivery member. As the distal end of the sheath extendsdistally, the effective length of the elongated opening in the distalsection of the delivery member is shortened and the radius of curvatureof the distal section of the EP device is correspondingly decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in section, of a mapping andablation assembly embodying features of the invention.

FIG. 2 is a transverse cross-sectional view of the assembly shown inFIG. 1 taken along the lines 2-2.

FIG. 3 is a transverse cross-sectional view of the assembly shown inFIG. 1 taken along the lines 3-3.

FIG. 4 is an elevational view, partially in section, of an EP devicesuitable for use with the assembly shown in FIGS. 1-5.

FIG. 5 is a transverse cross-sectional view of the EP device shown inFIG. 4 taken along the lines 5-5.

FIG. 6 is a longitudinal cross-sectional view of an alternativeembodiment similar to that shown in FIG. 1 wherein a lumen is providedto deliver fluid to the distal extremity of the assembly.

FIG. 7 is a transverse cross-sectional view of he assembly shown in FIG.6 taken along the lines 6-6.

FIG. 8 is a longitudinal cross-sectional view of an alternativeembodiment similar to that shown in FIG. 6 with a lumen extending fromthe proximal end of the assembly to the distal end of the assembly.

FIG. 9 is a transverse cross-sectional view of he assembly shown in FIG.8 taken along the lines 9-9.

FIG. 10 is a transverse cross-sectional view of he assembly shown inFIG. 8 taken along the lines 10-10.

FIG. 11 is an elevational view, partially in section, of anotheralternative embodiment wherein the delivery member is provided withelectrodes for sensing and/or ablation.

FIG. 12 is a transverse cross-sectional view of the embodiment shown inFIG. 11 taken along the lines 12-12.

FIG. 13 is an elevational view of another embodiment wherein the EPdevice of the assembly is provided with an inner lumen for delivery offluid.

FIG. 14A is a transverse cross-sectional view of the embodiment shown inFIG. 13 taken along the lines 14-14.

FIG. 14B is a transverse cross-sectional view of an alternativeembodiment of that shown in FIG. 13 taken along the lines 14-14.

FIG. 15 is an elevational view, partially in section, of a distalsection of an alternative embodiment wherein the EP device is providedwith an inner lumen for passage of fluid coolant.

FIG. 16 is a transverse cross-sectional view taken along the lines16-16.

FIG. 17 is an elevational view, partially in section, of a distalsection of an alternative embodiment wherein an outer sheath is disposedabout the assembly which is longitudinally movable to control theeffective length of the elongated opening in the distal section of thedelivery member.

FIG. 18 is an elevational view, partially in section, of an alternativeembodiment wherein a longitudinally movable flush sheath is providedabout the EP device of the assembly to delivery fluid to desiredlocations on the distal section thereof.

FIG. 19 is a transverse cross-sectional view of the embodiment shown inFIG. 18 taken along the lines 19-19.

FIG. 20 is an elevational view, partially in section, of a mapping andablation assembly embodying features of the invention.

FIG. 21 is a transverse cross-sectional view of the assembly shown inFIG. 20 taken along the lines 21-21.

FIG. 22 is a transverse cross-sectional view of the assembly shown inFIG. 1 taken along the lines 22-22.

FIG. 23 is an elevational view, partially in section, of an alternativeembodiment of the assembly shown in FIG. 20 having an elongateddepression.

FIG. 24 is a transverse cross-sectional view of the assembly shown inFIG. 24 taken along the lines 24-24

FIG. 25A is an elevational view, partially in section, of the proximalsection of an alternative embodiment of the assembly shown in FIG. 20having a deflection line.

FIG. 25B is an elevational view, partially in section, of the distalsection of an alternative embodiment of the assembly shown in FIG. 20having a deflection line.

FIGS. 26 and 27 are transverse cross-sectional view of the assemblyshown in FIG. 25 taken along lines 26-26 and 27-27, respectively.

FIG. 28 is an elevational view partially in section of a human hearthaving the assembly shown in FIG. 20 within the right atrium.

FIG. 29 is an elevational view, partially in section, of a distalsection of an alternative embodiment of the assembly shown in FIG. 20wherein an outer sheath is disposed about the assembly which islongitudinally movable to control the effective length of the elongatedopening in the distal section of the delivery member.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-3 schematically depict a mapping/ablation assembly 10 embodyingfeatures of the invention which generally comprises a delivery member 11and an elongated EP device 12 slidably disposed within the inner lumen13 of the delivery member 11 with the distal end of the EP devicesecured within the delivery member 11. An adapter 14 is provided on theproximal end of the delivery member 11 with a hemostatic valve 15 on theproximal end of the central arm 16 of the adapter and with a flush port17 in the proximal end of the side arm 18.

The delivery member 11 has a proximal shaft section 20 which is formedof a braided tubular structure 21 with a polymer impregnate 22incorporated therein. The braided structure 21 may be formed of highstrength filaments 23 (e.g. 6×6 strands) such as stainless steel wirewith a typical diameter of about 0.003 inch (0.08 mm). The polymerimpregnate is preferably a thermoplastic polyurethane such as PEBAX6333. An inner lining 24 of high strength polymer material such aspolyimide may be provided which extends to the start of the distalsection 25 of the delivery member 11.

A supporting ribbon 26 extends through the distal section 25 with theproximal extremity thereof about 5 to about 15 mm being secured to thebraided tubular structure 21 by suitable means such as solder oradhesive 27 within the wall of the proximal shaft section 30. Thesupporting ribbon 26 is generally about 6 to about 20 cm in total lengthand has a rectangular transverse cross-section of about 0.003-0.007 inchby 0.01-0.03 inch. The distal extremity of the supporting ribbon 26 issecured to the distal end of the delivery member 11 in a similarfashion. As shown in FIGS. 1 and 3, the braided tubular structure 21extends into the distal section 25 of the delivery member 11 disposedabout the supporting ribbon 26.

The distal section 25 of the delivery member 11 has an elongated opening28 which allows a distal section 31 of the EP device 12 to be extendedout and away from the distal section 25 of the delivery member 11 whenan axial compressive force is applied to the proximal extremity of theEP device which extends out of the patient during the procedure. Thelength of the elongated opening 28 is generally the same length as thedistal section 25, i.e. about 3 to about 20 cm. The width of theelongated opening 28 generally is greater than the diameter of thedistal section 31 of the EP device 12 to allow for the ready outwardmovement of the EP device.

In an alternative embodiment illustrated in FIG. 20, the distal section25 of the delivery member 11 is shapeable to a curved configuration withan elongated opening 60 along an inner side of the curved distal section25. The distal end of the EP device 12 is secured within the distal endof the elongated delivery member. The distal section 31 of the EP device12 is configured to extended out and away from the distal section 25 ofthe delivery member 11 through the elongated opening 60 when an axialelongating force is applied to the proximal extremity of the EP devicewhich extends out of the patient during the procedure. Thus, when the EPdevice is displaced proximally relative to the delivery member, as whenthe proximal extremity of the EP device is pulled proximally, the distalsection 31 of the EP device extends out the opening 60 in the distalsection 25 along an inner side of the curved distal section 25. FIGS. 21and 22 illustrate transverse cross sections of the assembly shown inFIG. 20 taken along lines 21-21 and 22-22, respectively.

In an alternative embodiment illustrated in FIG. 23, the elongatedopening 28/60 is omitted and the delivery member 11 has an elongateddepression along a side of the curved distal section 25, and an openingat a proximal end of the depression in fluid communication with theinner lumen 13. The depression is distal to the lumen 13 containing aproximal section of the EP device 12, and the EP device distal section31 extends distally of the lumen 13 out the opening at the proximal endof the depression. The distal section 31 of the EP device is configuredto extend away from the elongated depression when the EP device isdisplaced relative to the delivery member. FIG. 24 illustrates atransverse cross-sectional view of the assembly shown in FIG. 23 takenalong line 24-24.

The EP device 12, as shown in FIGS. 1 and 4-5 includes a proximal shaftsection 30 and a distal shaft section 31. The distal shaft section 31has a plurality of mapping/ablation electrodes 32 with each of theelectrodes electrically connected to separate electrical conductors 33(shown in FIGS. 4-5). The electrodes 32 are generally not larger thanabout 1.5 mm (4 Fr.), preferably less than 1.3 mm (3.5 Fr.) in outertransverse dimensions. The electrode length may vary from about 1 toabout 6 mm, preferably about 1 to about 3 mm, and the interelectrodespacing may vary from about 0.5 to about 4 mm, preferably about 0.5 toabout 2 mm. The electrodes 32 may be in the form of metallic cylindricalbands, helical coils, arcuate bands or ribbons and the like. The onlyportion of the electrodes 32 which need exposure are those surfaceswhich are to be in contact with the inner surface of the heart chamberto detect electrical activity or effect a linear ablation.

A suitable EP device 12 shown in detail in FIGS. 4 and 5, has proximaland distal shaft sections 30 and 31, an electrical connector 34 on theproximal end of the device and eight electrodes 32 on the distal section31 which are electrically connected to insulated electrical conductorsas in copending application Ser. No. 09/104,752, entitled E P Catheter,filed Jun. 25, 1998, and Ser. No. 08/188,619, U.S. Pat. No. 5,509,411,entitled Intravascular Sensing Device, filed on Jan. 27, 1994, which areincorporated herein in their entireties by reference. Core member 35extends to the distal end of the device which is secured to the distalend of coil 36 by suitable material such as a gold-tin solder (80%Au-20% Sn). The coil 36 is preferably a 90% Pt-10% Ir wire about 0.005inch in diameter. Polyimide tubing 37, about 0.001 inch thick, jacketsthe core member 35 proximal to the coil 36 which is in turn covered witha fluoropolymer tube 38 such as THV 200G which is available from 3M. Thebraided electrical conductors 33 are formed of 36 AWG copper wire witheach conductor having a polyimide insulating coating of about 0.0005inch thick (0.013 mm). An equivalent number of polyester fibers 39 (e.g.Dacron® from Dupont) are braided with the electrical conductors 33. Thebraided structure formed by the electrical conductors 33 and thepolyester strands 39 are covered by an additional fluoropolymer jacketor coating 40, preferably THV 200 g made by 3M. The electrodes 32 arehelical coils which are preferably formed form 90% Pt-10% Ir wire about0.005 inch (0.13 mm) in diameter.

The overall length of the delivery member 11, excluding the adapter 14,is about 110 to about 130 cm and the outer diameter is about 0.06 toabout 0.08 inch (1.5-2.0 mm). The inner lumen 13 is slightly larger thanthe outer diameter of the EP device 12 and generally is about 0.035 toabout 0.055 inch (0.9-1.4 mm). The EP device 12 has a working length ofabout 110-155 cm and a total length of about 135 to about 175 includingthe electrical connector 34.

The assembly of the invention may be introduced into the patient'svascular system, e.g. the femoral vein, percutaneously or by way of acut-down, advanced therein and through the inferior vena cava until thedistal section 25 is disposed within the right atrium. The supportingribbon 26 in the distal shaft section 31 is shaped into a curvedconfiguration so that it assumes the curved configuration whenunrestrained within the heart chamber. With the supporting ribbon actingas a supporting surface, a compressive force is applied to the proximalextremity of the EP device which extends out of the patient to urge thedevice in the distal direction, causing the distal shaft section 31 ofthe EP device 12 to bow outwardly away from the distal section of thedelivery member 11 and the support ribbon 26 therein. Alternatively, inthe embodiment illustrated in FIG. 20 having an elongated opening 60along an inner side of the curved distal section 25, the EP device isdisplaced proximally relative to the delivery member so that the distalsection of the EP device extends through the elongated opening 60 in thedistal section of the delivery member.

The delivery member 11 distal section may be shaped or shapeable into acurved configuration. The terms shaped or shapeable should not beunderstood to require a permanently curved section, and instead alsoinclude a reversibly deflectable section. In one embodiment, thesupporting ribbon 26 is shaped into a curved configuration, asillustrated in FIG. 20, so that it assumes the curved configuration whenunrestrained within the heart chamber. In an alternative embodiment thedelivery member 11 includes an elongated deflection line which deflectsthe delivery member distal section. In the embodiment illustrated inFIGS. 25-27, an elongated deflection line 62 is provided in a wall ofthe delivery member for deflecting the distal section 25 of the deliverymember 11 relative to the delivery member longitudinal axis. Thedeflection line is displaced longitudinally relative to the deliverymember to shape the delivery member distal section to the curvedconfiguration. The deflection line may be used alone or in combinationwith the supporting ribbon to cause the distal section of the deliverymember to assume the curved configuration. Moreover, the relativemovement affected between the EP device and the delivery member may beused to produce additional deflection of the distal section 25 of thedelivery member 11 relative to the delivery member longitudinal axis.FIG. 28 illustrates the assembly 10 shown in FIG. 20 within the rightatrium 71 of a human heart 70. While the deflection line is shown in theembodiment of the delivery member 11 illustrated in FIGS. 25-27, itshould be understood that the deflection line may be included in thealternative embodiments of the delivery member 11 illustrated in FIGS.1, 20 and 23. With the delivery member distal section in the curvedconfiguration illustrated in the figures, as for example in FIGS. 20 and23, the EP device distal section is in a curved configuration thatfollows the curve of the delivery member distal section and extends awayfrom the delivery member distal section to provide good contact againstthe heart wall.

Torquing the proximal section 30 of the delivery member 11, whichextends out of the patient during the procedure, will cause the distalsection 25 thereof to be rotatably displaced within the atrial chamberand allow the EP device 12 to be bowed outwardly in a wide variety ofdirections so electrical activity can be detected in a linear fashionand heart tissue can be linearly ablated at a number of locations withinthe chamber. When sensing electrical activity essentially all of theelectrodes 32 can be simultaneously employed, but, when performing alinear ablation, the typical procedure is to direct the RF current toone or two electrodes at the most distal end of the EP device to performthe first ablation and then continue proximally one or two electrodes ata time until a linear ablation of desired length is obtained in theatrial chamber. This reduces the overall power requirements for theassembly.

The electrodes 32 heat up due to the conductive heat transfer from thetissue being ablated and it is preferred to bath the electrodes withcooling fluid during the procedure to minimize the formation ofthrombus. While not shown in the drawings, thermocouples, thermistors orother temperature sensing means may be incorporated into the wall of theEP device 12 to detect the temperature of the electrodes or device wall.The flow of cooling fluid may be controlled to bathe the distal shaftsection 31 of the EP device 12 based upon the temperature sensed by thetemperature sensing means.

After the ablation, the electrodes 32 can be employed to detectelectrical activity to ensure that the ablation has been effective interminating the fibrillation or flutter. The electrodes 32 are muchsmaller in diametrical dimensions than prior ablation electrodes whichare usually about 1.5 mm or larger. Surprisingly, it has been found thatthe much smaller electrodes of the present invention provide effectiveablation through the atrial w-all without the power requirements of theprior electrodes. The elongated lesion formed by the linear ablationwith the smaller electrodes, while much thinner than lesions formed withthe prior larger electrodes, is quite effective in segregating hearttissue so as to terminate the fibrillation or flutter. Typically, theelongated lesion formed with the device of the present invention isabout 3 to about 12 mm, usually about 5 to about 10 mm, in width.

FIGS. 6 and 7 illustrate an alternative embodiment to that shown inFIGS. 1-3 wherein a second lumen 41 is provided within the distalsection of the delivery member in order to pass flushing or coolingfluids to the distal extremity of the delivery member. The spacingbetween the exterior of the EP device 12 and the inner surface of theinner lumen 13 of the delivery member 11 is minimized at location 42 sothat a significant portion of fluid passing through the inner lumen 13will pass through port 43 into the inner lumen 41. A discharge port 44is provided in the distal end of the delivery member 11 for discharge offluid from the inner lumen 41.

FIGS. 8-10 illustrate another embodiment similar in function to thatshown in FIGS. 7-8 which has a second lumen 45 extending the length ofthe delivery member 11 which is in fluid communication with a secondside arm 46 of the adapter 14. The other portions of the embodiment aresimilar to the embodiment shown in FIGS. 7-8 and are similarly numbered.

FIGS. 11-12 depict yet another embodiment similar in most regards tothat shown in FIG. 1 except that the delivery member 11 is provided witha plurality of electrodes 47 on the distal section 25 and at least oneelectrode 48 on the proximal shaft section 20. In this embodiment, thesurface of the electrodes 47 on the inside of the curved distal section25 need to be exposed. The electrodes 47 and 48 may be helical coils asshown or cylindrical tubes or arcuate ribbon or bands provided on theinside curve of the distal section 25. Individual electrical conductors(not shown) may be incorporated into the braided tubular structure 21and electrically connected by their distal ends to the electrodes 47 and48 and by their proximal ends to one or more electrical connectorsconfigured to be electrically connected to a high frequency electricalenergy source.

Another alternative embodiment of the invention is shown in FIGS. 13,14A and 14B wherein the EP device 12 is provided with an inner lumen 49for fluid delivery. An adapter 50 is secured to the proximal end of theEP device 12 to facilitate introduction of fluid to the inner lumen 49.In FIG. 14A the lumen 49 is off-set from the electrical conductors 51which are braided about the core 52, whereas, in FIG. 14B the lumen 49is formed by the braided conductors 51 within a polymer matrix 53. Theembodiment of FIG. 14B does not have a core member 52 as in FIG. 14A. Adischarge port 54 is provided in the distal end of the EP device 12which is in fluid communication with the inner lumen 49.

Alternative electrode details are illustrated in FIGS. 15 and 16 wherethe electrodes 32 are formed by a pair of inner and outer coils 55 and56 which are secured together at each end by solder, adhesive or thelike. The electrodes 32 are cooled by fluid flowing through the innerlumen 49. The coils may be expanded in the longitudinal direction toallow passage of fluid there through. A passageway (not shown) must beprovided through the wall of the EP device to facilitate the passage offluid. A single coil may be used for each electrode rather than a pairof coils 55 and 56 as shown.

In some instances it is desirable to change the curvature of the distalshaft section 31 of the EP device 12 when the distal end of the deviceis within the heart chamber to provide a better fit between the distalshaft section 31 and the inner surface of a heart chamber. To facilitatesuch changes, an outer sheath 57 may be provided about the exterior ofthe delivery member to effectively shorten the elongated opening 28/60in the distal section 25 of the delivery member 11 as shown in FIGS. 17and 29. By shortening the elongated opening 28 the radius of curvatureis reduced, as shown in phantom in FIGS. 17 and 29. Fluid may be passedthrough the inner lumen 58 of the sheath 57 to cool the electrodes 32during delivery of RF electrical energy. A variety of other means may beemployed to effectively shorten the elongated opening 28.

FIGS. 19 and 18 illustrate another method of cooling the electrodes 32on the distal section of the EP device 12 where a flushing sheath 59 isslidably disposed about the EP device. In this embodiment, the sheath 59can be longitudinally moved along the shaft of the EP device to exposeone or more electrodes 32. Fluid passing over the exposed electrode(s)while electrical energy is being delivered will cool the electrodessufficiently to avoid thrombus formation. Usually, electrical energy isnot directed to the entire array of electrodes at the same time due tothe rather large power requirements for such delivery. Electrical energyis preferably delivered to one or two of the most distal electrodeswhile fluid is delivered thereto until the lesion of desired length isformed. The sheath 59 is then pulled proximally to expose additionalelectrodes 32, electrical energy is delivered to one or two additionallyexposed electrodes while cooling fluid flows out of the distal end ofthe sheath 59. This procedure continues sequentially deliveringelectrical energy to the more proximal electrodes until a linearablation of the desired length is formed in the wall of the patient'sheart. The individual electrodes 32 may be used to detect electricalactivity after each individual ablation and after the entire linearablation procedure has been completed to determine if the fibrillationor flutter has been terminated.

While the invention has been described herein in terms or certainpreferred embodiments directed to the treatment of atrial fibrillationand flutter, those skilled in the art will recognize that the inventionmay be employed in a wide variety of procedures where an elongatedlesion is to be formed. Moreover, although individual features ofembodiments of the invention may be shown in some of the drawings andnot in others, those skilled in the art will recognize that individualfeatures of one embodiment of the invention can be combined with any orall the features of another embodiment. A variety of modifications andimprovements may be made to the present invention without departing fromthe scope thereof.

1. An intravascular assembly for forming a continuous lesion within achamber of a patient's heart, comprising: a) an elongated deliverymember having proximal and distal ends, an inner lumen extending thereinto the distal end, a distal section shapeable into a curvedconfiguration having an inner side and an outer side, an elongatedopening in the inner side of the curved distal section in communicationwith the inner lumen and an elongated support element which is fixedalong a length of the distal section coextensive with at least part ofthe elongated opening; and b) an elongated electrophysiological devicedisposed within the inner lumen of the elongated delivery member, havinga distal end secured within the distal end of the elongated deliverymember, and having a plurality of emitting electrodes on a distalportion thereof, and which is configured to extend out of the elongatedopening along the inner side of the delivery member curved distalsection upon relative movement between the delivery member and theelongated EP device, a plurality of electrical conductors havingproximal and distal ends with individual electrical conductors beingelectrically connected by their distal ends to emitting electrodes onthe distal portion of the electrophysiological device and by theirproximal ends to an electrical connector suitable for connection to asource of high frequency electrical energy.
 2. The intravascularassembly of claim 1 wherein the distal section of the elongated deliverymember is shaped to facilitate entry and positioning within thepatient's heart chamber.
 3. The intravascular assembly of claim 1wherein the support element within the distal section is a metallicribbon.
 4. The intravascular assembly of claim 3 wherein the metallicribbon has a flat surface facing the elongated opening.
 5. Theintravascular assembly of claim 1 wherein the electrodes on the distalportion of the electrophysiological device are not more than 1.35 mm indiameter.
 6. The intravascular assembly of claim 1 including alongitudinally movable sheath disposed about the delivery member tocontrol the length of the elongated opening.
 7. The intravascularassembly of claim 6 wherein the outer sheath has a curved distalextremity.
 8. The intravascular assembly of claim 1 including alongitudinally movable sheath disposed about the EP device having aproximal end configured to be connected to a source of fluid and adistal end extending over the distal extremity of the EP device.
 9. Theintravascular assembly of claim 1 including a second inner lumenextending within at least the distal section of the elongated deliverymember to a discharge port in the distal end of the elongated deliverymember.
 10. The intravascular assembly of claim 9 wherein the secondinner lumen extends from the proximal end of the elongated deliverymember to the distal end thereof.
 11. The intravascular assembly ofclaim 1 including a longitudinally movable outer sheath disposed aboutthe intravascular device to control the length of the elongated openingwhich is exposed.
 12. The intravascular assembly of claim 1 wherein theelongated delivery member is provided with at least one electrode on thedistal section thereof.
 13. The intravascular assembly of claim 1wherein the distal section of the elongated delivery member is providedwith a lumen for delivery of cooling fluid to the distal end of theassembly.
 14. The intravascular assembly of claim 13 wherein the lumenfor delivery of the cooling fluid extends to the proximal end of theassembly.
 15. The intravascular assembly of claim 3 wherein a multi-armadapter is provided on the proximal end of the assembly which has an armwith an inner lumen in fluid communication with the lumen for deliveryof the cooling fluid.
 16. The intravascular assembly of claim 1including an elongated deflection line secured to the distal end of thedelivery member.
 17. A method for treating a patient's heart forfibrillation or flutter comprising: a) providing a intravascularassembly including. an elongated delivery member having proximal anddistal ends, an inner lumen extending therein to the distal end, adistal section shapeable to a curved configuration having an inner sideand an outer side, an elongated opening in the inner side of the curveddistal section in communication with the inner lumen, and an elongatedsupport element which is fixed along a length of the distal sectioncoextensive with at least part of the elongated opening; and anelongated electrophysiological device disposed within the inner lumen ofthe elongated delivery member, having a plurality of emitting electrodeson a distal portion thereof, and which is configured to extend out ofthe elongated opening along the inner side of the delivery member curveddistal section upon relative movement between the delivery member andthe elongated electrophysiological device; b) introducing theintravascular assembly into the patient's vasculature and advancing theassembly therein until the distal portion of the assembly is disposedwithin a chamber of the patient's heart; c) effecting relative movementbetween the electrophysiological device and the delivery member bydisplacing the electrophysiological device proximally relative to thedelivery member so that the distal section of the electrophysiologicaldevice extends through the elongated opening in the distal section ofthe delivery member; d) contacting the extended distal section of theelectrophysiological device with a desired surface of the heart chamber;e) delivering high frequency electrical energy to at least one electrodeon the electrophysiological device to form a first lesion on the surfaceof the heart chamber; and f) delivering high frequency electrical energyto at least one other electrode on the electrophysiological device toform at least a second lesion on the surface of the heart chamberadjacent to a previously formed lesion thereon.
 18. The method of claim17 wherein the electrodes on the electrophysiological device are bathedin cooling fluid when emitting high frequency electrical energy.
 19. Themethod of claim 17 wherein an outer sheath is disposed about theintravascular assembly and the longitudinal position of the outer sheathabout the intravascular assembly is adjusted to control the length ofthe elongated opening in the elongated delivery member which in turncontrols the curvature of the distal section of the electrophysiologicaldevice which extends out of the elongated opening.
 20. An intravascularassembly for forming a continuous lesion within a chamber of a patient'sheart, comprising: a) an elongated delivery member having proximal anddistal ends, an inner lumen extending within at least a section of thedelivery member, a distal section shapeable into a curved configurationhaving an inner side and an outer side; and b) an elongatedelectrophysiological device having a distal end secured to the distalend of the elongated delivery member, and having a distal sectionshapeable into a curved configuration which is configured to follow thedelivery member curved distal section and extend away from the deliverymember curved distal section, and having a plurality of emittingelectrodes on a distal portion thereof, a plurality of electricalconductors having proximal and distal ends with individual electricalconductors being electrically connected by their distal ends to emittingelectrodes on the distal portion of the electrophysiological device andby their proximal ends to an electrical connector suitable forconnection to a source of high frequency electrical energy.
 21. Theintravascular assembly of claim 20 wherein the delivery member distalsection is deflectable and including an elongated deflection linesecured to the distal end of the delivery member. 22-24. (Cancelled) 25.A method for treating a patient's heart for fibrillation or fluttercomprising: a) providing an intravascular assembly including anelongated delivery member having proximal and distal ends, an innerlumen extending within at least a section of the delivery member, adistal section shapeable into a curved configuration having an innerside and an outer side; and an elongated electrophysiological devicehaving a distal end secured to the distal end of the elongated deliverymember, and having a distal section shapeable into a curvedconfiguration which is configured to follow the delivery member curveddistal section and extend away from the delivery member curved distalsection, and having a plurality of emitting electrodes on a distalportion thereof, a plurality of electrical conductors having proximaland distal ends with individual electrical conductors being electricallyconnected by their distal ends to emitting electrodes on the distalportion of the electrophysiological device and by their proximal ends toan electrical connector suitable for connection to a source of highfrequency electrical energy; b) introducing the intravascular assemblyinto the patient's vasculature and advancing the assembly therein untilthe distal portion of the assembly is disposed within a chamber of thepatient's heart; c) deflecting the distal sections of the deliverymember and the electrophysiological device into the curved configurationso that the distal section of the electrophysiological device followsthe distal section of the delivery member; d) effecting relativemovement between the electrophysiological device and the delivery memberby displacing the electrophysiological device proximally relative to thedelivery member so that the distal section of the electrophysiologicaldevice extends away from the distal section of the delivery member; e)contacting the extended distal section of the electrophysiologicaldevice with a desired surface of the heart chamber; f) delivering highfrequency electrical energy to at least one electrode on theelectrophysiological device to form a first lesion on the surface of theheart chamber; and g) delivering high frequency electrical energy to atleast one other electrode on the electrophysiological device to form atleast a second lesion on the surface of the heart chamber adjacent to apreviously formed lesion thereon.
 26. An intracorporeal assembly forforming a continuous lesion, comprising: a) an elongated delivery memberhaving proximal and distal ends, a distal section shapeable into acurved configuration having an inner side and an outer side, anelongated opening in one of the inner or outer sides of the curveddistal section and an elongated support element which is fixed along alength of the distal section coextensive with at least part of theelongated opening; and b) an elongated electrophysiological device whichis disposed within the elongated delivery member, which has a distal endsecured within the distal end of the elongated delivery member, andwhich has a plurality of emitting electrodes on a distal portionthereof, and which is configured to extend out of the elongated openingalong the inner or outer side of the delivery member curved distalsection upon relative movement between the delivery member and theelongated electrophysiological device.
 27. The intracorporeal assemblyof claim 26 wherein the elongated delivery member has an inner lumenextending therein.
 28. The intracorporeal assembly of claim 27 whereinthe side opening is in communication with the inner lumen.
 29. Theintracorporeal assembly of claim 27 wherein elongatedelectrophysiological device is disposed within the inner lumen of theelongated delivery member.
 30. The intracorporeal assembly of claim 26wherein elongated opening is in the inner side of the elongated deliverymember.
 31. The intracorporeal assembly of claim 26 wherein theelectrophysiology device has a plurality of electrical conductors havingproximal and distal ends with individual electrical conductors beingelectrically connected by their distal ends to emitting electrodes onthe distal portion of the electrophysiological device and by theirproximal ends to an electrical connector suitable for connection to asource of high frequency electrical energy.
 32. The intracorporealassembly of claim 26 wherein the distal section of the elongateddelivery member is shaped to facilitate entry and positioning within thepatient's heart chamber.
 33. The intracorporeal assembly of claim 26wherein the support element within the distal section is a metallicribbon.
 34. The intracorporeal assembly of claim 33 wherein the metallicribbon has a flat surface facing the elongated opening.
 35. Theintracorporeal assembly of claim 26 wherein the electrodes on the distalportion of the electrophysiological device are not more than 1.35 mm indiameter.
 36. The intracorporeal assembly of claim 26 including alongitudinally movable sheath disposed about the delivery member tocontrol the length of the elongated opening.
 37. The intracorporealassembly of claim 36 wherein the outer sheath has a curved distalextremity.
 38. The intracorporeal assembly of claim 26 including alongitudinally movable sheath disposed about the EP device having aproximal end configured to be connected to a source of fluid and adistal end extending over the distal extremity of the EP device.
 39. Theintracorporeal assembly of claim 26 including a second inner lumenextending within at least the distal section of the elongated deliverymember to a discharge port in the distal end of the elongated deliverymember.
 40. The intracorporeal assembly of claim 39 wherein the secondinner lumen extends from the proximal end of the elongated deliverymember to the distal end thereof.
 41. The intracorporeal assembly ofclaim 26 including a longitudinally movable outer sheath disposed aboutthe intravascular device to control the length of the elongated openingwhich is exposed.
 42. The intracorporeal assembly of claim 26 whereinthe elongated delivery member is provided with at least one electrode onthe distal section thereof.
 43. The intracorporeal assembly of claim 26wherein the distal section of the elongated delivery member is providedwith a lumen for delivery of cooling fluid to the distal end of theassembly.
 44. The intracorporeal assembly of claim 43 wherein the lumenfor delivery of the cooling fluid extends to the proximal end of theassembly.
 45. The intracorporeal assembly of claim 43 wherein amulti-arm adapter is provided on the proximal end of the assembly whichhas an arm with an inner lumen in fluid communication with the lumen fordelivery of the cooling fluid.
 46. The intracorporeal assembly of claim26 including an elongated deflection line secured to the distal end ofthe delivery member.
 47. A method for treating a patient's heart,comprising: a) providing an intracorporeal assembly including anelongated delivery member which has proximal and distal ends, a distalsection shapeable into a curved configuration having an inner side andan outer side; and an elongated electrophysiological device having adistal end secured to the distal end of the elongated delivery member,and having a distal section shapeable into a curved configuration whichis configured to follow the delivery member curved distal section andextend away from the delivery member curved distal section, and having aplurality of emitting electrodes on a distal portion thereof; b)introducing the intravascular assembly into the patient's vasculatureand advancing the assembly therein until the distal portion of theassembly is disposed tissue of the patient's heart; c) deflecting thedistal sections of the delivery member and the electrophysiologicaldevice into the curved configuration so that the distal section of theelectrophysiological device follows the distal section of the deliverymember; d) effecting relative movement between the electrophysiologicaldevice and the delivery member by displacing the electrophysiologicaldevice proximally relative to the delivery member so that the distalsection of the electrophysiological device extends through the elongatedopening in the side of the delivery member away from the distal sectionthereof; e) contacting the extended distal section of theelectrophysiological device with desired heart tissue; and f) deliveringhigh frequency electrical energy to a plurality of electrodes on theelectrophysiological device to form a first lesion on the surface of theheart tissue.
 48. The method of claim 47 wherein high frequencyelectrical energy is delivered to at least one of the electrodes on theelectrophysiological device to form at least a second lesion on thesurface of the heart tissue adjacent to a previously formed lesionthereon.
 49. A method for treating a patient's heart, comprising thesteps of: a) providing an intracorporeal assembly including an elongateddelivery member which has proximal and distal ends, a distal sectionshapeable into a curved configuration having an inner side and an outerside; and an elongated electrophysiological device having a distal endsecured to the distal end of the elongated delivery member, and having adistal section shapeable into a curved configuration which is configuredto follow the delivery member curved distal section and extend away fromthe delivery member curved distal section, and having a plurality ofemitting electrodes on a distal portion thereof,; b) introducing theintravascular assembly into the patient's vasculature and advancing theassembly therein until the distal portion of the assembly is disposedtissue of the patient's heart; c) deflecting the distal sections of thedelivery member and the electrophysiological device into the curvedconfiguration so that the distal section of the electrophysiologicaldevice follows the distal section of the delivery member; d) effectingrelative movement between the electrophysiological device and thedelivery member by displacing the electrophysiological device proximallyrelative to the delivery member so that the distal section of theelectrophysiological device extends through the elongated opening in theside of the delivery member away from the distal section thereof; e)contacting the extended distal section of the electrophysiologicaldevice with desired heart tissue; and f) delivering high frequencyelectrical energy to a plurality of electrodes on theelectrophysiological device to form a first lesion on the surface of theheart tissue.
 50. The method of claim 49 including the step ofdelivering high frequency electrical energy delivered to at least one ofthe electrodes on the electrophysiological device to form at least asecond lesion on the surface of the heart tissue adjacent to apreviously formed lesion thereon.